Document WO98/26489 describes an apparatus for evenly apportioning the electrical loads on a polyphase power distribution network. Current probes perform a measurement of current for each incoming phase and in each branch of the supplied network. A processor analyses the measurements of the current probes. Each branch comprises a multipole switch and an isolator. The processor is connected to each breaker so as to selectively connect each branch to a single appropriate phase after having interrupted its power supply by means of its isolator. Thus, the electrical loads are apportioned by the processor over the various phases.
In electrical networks, the transport of electricity is generally performed by three-phase networks up to the distribution site. For reasons of structural simplicity and voltage level, most loads connected to the electrical network are single-phase loads. A single-phase load is connected between a phase and the neutral of the three-phase network. A large number of single-phase loads is generally connected to the three-phase network. On account of the power differences of the loads connected to these three phases, the three-phase network experiences imbalances between the phases. The currents drawn by the various phases are then different, and this may lead to voltage drops, energy losses, limitation of the number of connectable loads, degradation of the quality of the current, and/or overload of the electricity generator. When a photovoltaic installation supplies the three-phase network, it may even turn out to be necessary to inject current from an external network based on other energy sources in order to balance the currents on the various phases.
When the utility operating the three-phase electrical network notes recurring phase imbalances, it undertakes rebalancings. Within the framework of electrical networks, the loads are usually single-phase transformers which provide energy to a small group of dwellings. When a recurring phase imbalance is noted, a new distribution of the loads is designed. A technician then intervenes directly on one or more transformers to connect them to other phases.
To avoid having to design the new distribution of the loads empirically, the document entitled “phase swapping for distribution system using tabu search” proposes an algorithm for optimizing the distribution of these loads.
Even when optimizing the distribution of the loads on the three-phase network, manual technical intervention remains necessary, thereby greatly limiting the frequency of the achievable modifications of distribution. Such intervention furthermore requires a shutdown of one or more loads, thereby limiting the possible frequency at which it can be carried out. A shutdown of a load may also turn out to be incompatible with its operation, certain loads having to remain in continuous service, for example computer servers or medical equipment. Such a redefinition of the load distributions is therefore performed only when truly necessary, to the detriment of the balance between the phases over long periods.